Actions of an external electrical shock on human atrial excitation - A computer model study

Abstract

Atrial fibrillation (AF) is one of the most common cardiac diseases that cause morbidity and mortality. One of the most frequently used clinical treatments of AF is to use a large and brief external electrical shock to reset atrial tissue from a disordered fibrillation state to a quiescent state, then the pacemaker of the heart resumes its control of atrial excitation rhythm and thus a defibrillation is achieved. Though widely used in practice, the mechanisms underlying the success of an electrical shock in defibrillation is incompletely understood. In this study, we developed a computer model of human atrial tissue to investigate the actions of an external electrical shock on atrial excitations. Using the model, we computed the defibrillation threshold of the human atrium. We found that due to the supernormal excitability of human atrium, the computed successful defibrillation threshold is much less than the excitation threshold of human atrium in resting state. This study provides some new insights to understand the mechanisms underlying AF defibrillation. © Springer-Verlag Berlin Heidelberg 2007.